Carbon Quantum Dots from Roasted Coffee Beans: Their Degree and Mechanism of Cytotoxicity and Their Rapid Removal Using a Pulsed Electric Field

Ling Chu; Yu Zhang; Leli He; Qingwu Shen; Mingqian Tan; Yanyang Wu

doi:10.3390/foods12122353

Carbon Quantum Dots from Roasted Coffee Beans: Their Degree and Mechanism of Cytotoxicity and Their Rapid Removal Using a Pulsed Electric Field

Foods. 2023 Jun 13;12(12):2353. doi: 10.3390/foods12122353.

Authors

Ling Chu¹, Yu Zhang¹, Leli He¹, Qingwu Shen¹, Mingqian Tan², Yanyang Wu^{1

2

3

4

5}

Affiliations

¹ Key Laboratory for Food Science and Biotechnology of Hunan Province, College of Food Science and Technology, Hunan Agricultural University, Changsha 410128, China.
² School of Food Science and Technology, National Engineering Research Center of Seafood, Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian 116034, China.
³ Horticulture and Landscape College, Hunan Agricultural University, Changsha 410128, China.
⁴ Hunan Co-Innovation Center for Utilization of Botanical Functional Ingredients, Changsha 410128, China.
⁵ State Key Laboratory of Subhealth Intervention Technology, Changsha 410128, China.

Abstract

Carbon quantum dots (CQDs) from heat-treated foods show toxicity, but the mechanisms of toxicity and removal of CQDs have not been elucidated. In this study, CQDs were purified from roasted coffee beans through a process of concentration, dialysis and lyophilization. The physical properties of CQDs, the degree and mechanism of toxicity and the removal method were studied. Our results showed that the size of CQDs roasted for 5 min, 10 min and 20 min were about 5.69 ± 1.10 nm, 2.44 ± 1.08 nm and 1.58 ± 0.48 nm, respectively. The rate of apoptosis increased with increasing roasting time and concentration of CQDs. The longer the roasting time of coffee beans, the greater the toxicity of CQDs. However, the caspase inhibitor Z-VAD-FMK was not able to inhibit CQDs-induced apoptosis. Moreover, CQDs affected the pH value of lysosomes, causing the accumulation of RIPK1 and RIPK3 in lysosomes. Treatment of coffee beans with a pulsed electric field (PEF) significantly reduced the yield of CQDs. This indicates that CQDs induced lysosomal-dependent cell death and increased the rate of cell death through necroptosis. PEF is an effective way to remove CQDs from roasted coffee beans.

Keywords: carbon quantum dots; coffee; cytotoxicity; pulsed electric field.

Grants and funding

This research was funded by the National Natural Science Foundation of China (32072334) and the National Natural Science Foundation of Hunan Province, China (2020JJ4362).